Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

积层多层板用UV油墨的合成研究

采用丙烯酸改性环氧树脂E－44的方法，合成了环氧丙烯酸酯预聚物，并将其用在UV光固化油墨的配方中。在树脂合成过程中，研究了反应温度，催化剂，阻聚剂等因素对合 产品的影响。通过L9(3^4)正交试验，得到了优化的工艺参数：反应温度为90℃，催化剂为N，N－二甲苯胺，用量1％；阻聚剂对苯二酚，用量0．5％，投料环氧树脂和丙烯酸的摩尔比为1：1．08。     

Effect of SiO2 addition on the dielectric properties and microstructure of BaTiO3-based ceramics in reducing sintering

The effect of SiO2 doping on the sintering behavior,microstructure,and dielectric properties of BaTiO3-based ceramics has been investigated.Silica was added to the BaTiO3-based powder prepared by the solid state method with 0.075mo1%,0.15mo1%,and 0.3mo1%,respectively.The SiO2-doped BaTiO3-based ceramic with high density and uniform grain size were obtained,which were sintered in reducing atmosphere.A scanning electron microscope,X-ray diffraction,and LCR meter were used to determine the microstructure as well as the dielectric properties.SiO2 can form a liquid phase belonging to the ternary system of BaO-TiO2-SiO2,leading to the formation of BaTiO3 ceramics with high density at a lower sintering temperature.The SiO2-doped BaTiO3-based ce-ramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h.The dielectric constants of the sample with 0.15mo1% SiO2 addition sintered at 1220℃ is about 9000.Doping with a small amount of silica can improve the sinter-ing and dielectric properties of BaTiO3-based ceramics.     

基于纯声子散射模型的纳米薄膜热传导分析

起粘结作用的薄膜结构厚度达到纳米尺度时,应用由微尺度观点建立的非傅立叶热传导模型分析其性能。文章采用纯声子散射模型分析绝缘薄膜结构的温度场和热应力,并与用在宏观尺度下的傅立叶热传导模型所得结果进行比较,同时研究绝缘薄膜结构热物理性能参数对温度场和热应力的影响。研究表明：采用纯声子散射模型分析结果与傅立叶热传导模型所得结果有明显区别,绝缘薄膜结构热物理性能参数对温度场和热应力也有显著影响。     

磁控溅射AI／Pb纳米多层膜调制结构研究

用磁控交替沉积制备Al／Pb纳米多层膜,运用XPS,AFM,TEM考察表面状况及膜结构．结果表明,实验条件下,当Al层厚60nm时,Pb子层标定厚度从20nm增至30nm,可形成较完整埋层调制结构．随Pb层厚度增加,连续性变好、表面糙度降低,Al层对Pb层表面糙度克服能力提高,改善层状结构完整性．多层膜中Al,Pb子层均存在（111）择优取向特征,由fcc结构的表面自由能最小化引起．     

基于多层动态索引的相似炉型检索方法研究

针对炉型设计涉及的原始数据量庞大,合理炉型的界定范围广,界限模糊等问题,提出应用基于实例的推理方法辅助炉型初始方案的生成.分析了高炉炉型设计的特征属性,并建立了层次结构,针对其特征索引较多,权重系数小,检索效率低等问题,建立一种多层动态索引策略来改进传统的最近邻法,实现了炉型初始设计方案的智能生成.从而提高了相似实例检索的准确性和有效性,为后续对比调整提供了具有可比性和高参考价值的设计方案.     

微型足球机器人多层次分区和防守动作的设计

在分析了一些攻方机器人所采取的进攻策略,以及结合球队自身的实际情况后,为了提高防守的有效性和球队的整体防守能力,提出建立一种多层次防守体系,并设计了新的防守动作．试验结果表明,采用以上策略设计后,球队的整体防守能力得到了提高．     

人眼屈光度校正算法的研究现状

人类能够与用户图像界面进行交互是依赖于一个清晰正常的视觉。然而,屈光不正（例如近视、远视、散光等）能使人眼视网膜中所显示的图像质量退化。图像质量的好坏严重影响了我们在军事、医学、娱乐领域所取得的研究成果。目前,对于人眼屈光度校正算法的研究主要有五种方法：1.应用一个维纳滤波的预补偿算法来校正人眼屈光度;2.用一个全变差的方法绘制图像对人眼屈光度进行校正;3.用视觉分析系统来校正人眼屈光度;4.使用多层显示器来校正视觉畸变;5.使用可计算的光场显示器来校正视觉畸变。通过研究这几种算法的优缺点提出现有算法的改进以及新的算法研究。     

原位聚合法制备香精微胶囊的工艺优化研究

以低甲醚化蜜胺树脂为壁材,香精为芯材,采用原位聚合法制备了一系列香精微胶囊．通过对所制备的香精微胶囊进行显微观察、粒度分析、包裹率测试和稳定性考察,研究了工艺条件的影响,并对香精微胶囊的多层造壁效果进行了分析．结果表明,在搅拌速度为600r／min,壁材预聚体滴加时间为30min,50min缓慢升温至75℃保温固化的条件下所得到的香精微胶囊包覆效果良好,产品乳液稳定;双层壁材香精微胶囊的粒径分布最窄,而三层壁材的香精微胶囊具有最高的热稳定性,包裹率可达92．26％．